The present invention is in the field of motor-compressor assemblies.
More particularly, the present invention relates to hermetically sealed refrigeration motor-compressor assemblies for use in domestic appliances such as refrigerators, freezers and room air conditioners.
It has long been recognized in the art that mechanical noise generated by the moving parts of an operating motor-compressor assembly within a hermetically sealed shell could be transmitted to the shell and hence to the surrounding environment. A portion of the noise was transmitted to the shell via the conventional body of lubricating oil contained in a sump area of the shell, the lower part of the motor-compressor assembly being submerged in the body of oil. This portion of noise transmitted to the environment surrounding the hermetically sealed shell is undesirable and means to reduce such noise are of prime importance especially in the field of domestic appliances.
It has been further recognized in the art that aeration of the body of lubricating oil so as to cause foaming lessens considerably the sound transmitting quality of the oil.
Various means have been proposed for aerating the lubricating oil located in the sump area of the hermetically sealed shell. U.S. Pat. Nos. 3,066,857, 3,147,914, 3,480,205 and 3,614,384, assigned to the assignee of the present invention, disclose various means for aerating the lubricating oil.
While suitable aeration of the lubricating oil may be accomplished by means such as disclosed in the heretofore noted patents, the process of aeration may generate undesirable noise. Thus the gain in overall reduction of noise due to the sound attenuating qualities of the aerated oil may be set off by the increased noise generated by the aeration process.